The Research About The Phase-shift-full-bridge Circuit On Modeling And Control

With the development of power electronics technology,the application of DC-DC converters is becoming more and more widely.As a result of the advantages of high power,isolation of input and output,the application of wide range of applications,the full-bridge converter can realize ZVS soft-switching,further reducing the on-state loss of the converter and improving the transmission efficiency,and is widely used in aerospace,power system and other places where power quality has strict requirements.In this paper,the operation of ZVS full-bridge converter is studied systematically,and the current loop and duration of each switching mode are analyzed with half a switching period.The switching of diode on the secondary side of ZVS is studied.The conditions of ZVS are realized by the advanced and lagging arms respectively.In order to verify the working process of ZVS,an open-loop simulation model is built in Saber simulation software to verify the ZVS operating characteristic of the switch.At present,the transformer leakage inductance and ESR of the output filter capacitor are neglected when the state-space averaging method is used to model the full-bridge circuit.The obtained model can not accurately reflect the characteristics of the circuit.On this basis,an improved The model includes the leakage inductance of the transformer,the ESR of the output capacitor and the efficiency of the converter.The transfer function of the control to the output and the output impedance is deduced.The simulation model is validated by using the Saber model.The closed-loop control and stability of the phase-shifted full-bridge circuit are studied.The principle of the voltage control method and the current control method are analyzed.The design process of the compensator in the closed-loop system is also studied.In order to improve the performance of the controller,the application of fuzzy adaptive PID control method in the full-bridge converter is studied on the basis of the traditional PID control.The fuzzy rules are established based on the deviation of the output voltage and the rate of deviation,and then the fuzzy adaptive PID controller is designed,which makes the PID controller parameters can be adjusted dynamically and the system has better dynamic characteristics.In order to verify the performance of the designed Fuzzy PID controller,a closed-loop simulation model is built in Saber and Matlab/Simulink,and compared with the traditional PID controller.It can be seen from the comparison of the simulation results that the fuzzy adaptive PID control method has better stability and dynamic characteristics compared with the traditional PID mode,and has better performance on the large range of input voltage and load resistance of the system of the anti-jamming.